Jones Zone gap

In the covalent solids, the Jones Zone gap should be identified with the principal optical absorption peak previously identified with LCAO interatomic matrix elements. Thus it allows a direct relation between the parameters associated with the LCAO and with the pseudopotential theories. It is best, however, to simplify the pseudopotential analysis still further before making that identification. 

We found earlier in this ciiapter that this is the dominant matrix element that opens up the gap at the Jones Zone, eliminates tlie Fermi surface, and dominates the bonding properties. As we slowly displace the second sublattice, as in... 

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